Making a balloon canopy worked out way better for me than the balloon avalanche I previously pinned. Just tape two garbage bags to the ceiling and tuck the ends into the door. The birthday boy/girl is showered with balloons when they open it.
BALLOON AVALANCHE !!-Cut open one two plastic garbage bags. Use paper tape/masking tape to tape the bags to the outside of the door frame, leaving the top open. Blow up balloons, stuff ‘em in, and when the birthday boy or girl opens their door in the morning … balloon avalanche!